Control mechanism for pumps



1937. H. w. LANDENBERGER 2,098,425

CONTROL MECHANISM FOR PUMPS Filed March 26, 1935 5 Sheets-Sheet 1 k3[7778/7 for Nov. 9, 1937.

H. w. LANDENBElGER 2,098,425

CONTROL MECHANISM FOR PUMPS Filed March 26, 1935 3 Sheets-Sheet 2 Nov.9, 193 7.

CONTROL MECHANISM FOR PUMPS Filed March 26, 1955 3 Sheets-Sheet 5 50 R[Q 5 I 56 I Z I I 5/J 6- k7 Z0 -25 /.s /0 I /7 l? J r /4 /5 j 7 5 i z Z3i 1/ .aa 34 J3 z! w 23 I I a] II I 35 l Patented Nov. 9, 1193? UR ETSif: i.

signcr to American Engineering Company,

Philadelphia, Pa, a corporation of Pennsylvania Application March 26,1935, Serial No. 13,096

9 Claims.

This invention relates to control mechanisms, and, more particularly tomechanisms for controlling the operation of pumps.

One object of the present invention is to pro- 3 vide an improvedcontrol mechanism for pumps, which functions to maintain the pump onstroke throughout a predetermined pressure range in the system, toactuate the stroke adjusting means toward neutral position when thepressure in the system exceeds a predetermined value, and underpredetermined conditions to maintain the pump on leakage stroke at acomparatively low pressure.

A more specific object is to provide a control mechanism for pumps whichcomprises a pair of rams, one of said rams being constantly connected tothe pressure in the system while the other is connected thereto onlyunder predetermined conditions at which time both rams function tomaintain the pump on leakage stroke.

Other and further objects will become apparent as the description of theinvention progresses.

Of the drawings, Fig. 1 is a diagrammatic view of the fluid controlsystem showing certain of the elements thereof in section.

Fig. 2 is a side elevational view partly in section, of the highpressure pump and the control mechanism associated therewith.

Fig. 3 is a side elevational view of a portion of the control mechanismassociated with a high pressure pump.

Fig. 4 is a diagrammatic view partly in section of the hydraulic pressand a portion of the hydraulic circuit including the control'valves,showing the flow of fluid in the system when one of the valves is movedto its upper position of adjustment, and,

Fig. 5 is a similar view showing the flow of fluid in the system whenboth valves are.moved to their upper position of adjustment.

Referring to the drawings, the numeral 5 designates generally the fluidcontrol system, which in the present instance comprises a pump unit 2,manually actuated valves A and B, automatic valve C, and an hydraulicpress 3.

The pump unit 2 comprises a high pressure pump H and a low pressure pumpL, suitably mounted upon a supply or makeup tank T. Pumps H and L are ofthe general type shown and described in the United States Patent No.1,077,- 979, and in the present instance are driven by an electric motorM. Fluid is drawn into pump H from makeup tank '1 through a pipe 4, andis discharged from said pump through. a pipe 5. Pipe 5 is connected to acentral port 6 of valve A. 'In a like manner fluid is drawn into pump Lfrom tank T through a pipe land is discharged therefrom through a pipe8. Pipe 8 is connected to pipe 5 and by means of a check valve 9 areverse flow of fluid therein to pump L is prevented.

Valve A is provided with a substantially cylin- 5 drical chamber ill inwhich a pair of spaced interconnected valve members H and i2 operate.These valve members may be shifted by a lever I3 pivoted at one end to alink 14 which in turn is pivoted to a bracket l5 secured to andextending outwardly from valve A. Valve A in addition to port 6 hasprovided in the casing thereof ports l6 and I1, communicating withchamber l0, and a passage i9 which connects the opposite ends of chamberl0 communicates with a fourth port [8. 15

Press 3 comprises an upper cylinder having a piston 2| operatingtherein, a lower cylinder 22 having a piston 23 operating therein, andan intermediate stationary forming mold 24. Piston 2| is provided with areduced portion 25 form- 20 ing with the inner walls of cylinder 20 anannular chamber 26, and to the end of which is secured a forming platen21. Piston 23 has secured to the upper end thereof a holding platen 28.The purpose of platens 21 and 28 will appear fully 25 hereinafter.

Valve B is also provided with a cylindrical chamber 29 having spacedinterconnected valve members 30 and 3| operating therein. Valve members30 and 3| may be shifted by a lever and 30 link mechanism 32 similar tothat shown in connection with valve A. Valve B has provided in thecasing thereof ports 33, 34 and 35 which communicate with chamber 29.

Valve C comprises an upper chamber 36, an 35 intermediate chamber 31,and a lower chamber 38. The upper chamber 36 is connected to pipe 8 by abranch pipe 39, and has provided therein a valve 40 which normallyprevents the passage of fluid to intermediate chamber 31 through the 4connecting passage 4|. A coil spring 42 extends between valve 40 and aspring seat 43 provided at the upper end of said chamber and a set screw44 is provided to adjust the tension of said spring.

A pipe 45 connects intermediate chamber 3'l-with 4.5 makeup tank T.Lower chamber38 has provided therein a comparatively large piston 46,the reduced portion 41 of which extends upwardly through and is guidedin a cylindrical opening between chambers 31 and 38. The upper end ofreduced portion 41 engages the lower end of the stem 48 of valve 40. Apipe 49 connects pipe 5 with the lower end of chamber 38. It thereforeis evident that when the pressure in the system exce ds the tension ofspring 42 piston 46 will unseat valve 46 and thus permit the dischargeof pump L to bypassto makeup tank T through chamber 28, passage 4|,chamber 31 and pipe 45.

Returning to valves A and B, it is seen that a pipe 56 connects theupper end of cylinder 26 with port l6 of valve A. A pipe 5! connectsport I! of valve A with a pipe 52; one end of the latter is connected tothe lower end of cylinder 26, while the other end thereof is connectedto port 35 of valve B. A pipe 53 connects the lower end of cylinder 22with port 33 of valve B, and a pipe 54 connects port 34 with makeup tankT. A check valve 55 is provided in pipe 52 tonormally prevent a reverseflow of fluid from cylinder 22. A branch pipe 56 having a check valve 51provided therein connects pipes 56 and 52 as shown in Fig. 1, and a pipe58 connects port l6 of valve A with makeup tank T. A comparatively smallpipe 56 connects discharge pipe 5 of pump H with a fluid motor 66mounted at one end of pump H, while a second pipe 6| connects pipe 52with a second fluid motor 62 mounted at the opposite end of said pump.Fluid motor 66, therefore, is always connected to the pressure in thesystem, while fluid motor 62, it will be observed, is connected to thepressure in the system only when fluid enters the lower end of cylinder26.

Motor 66 in the present instance comprises a bracket 66 secured to thepump casing in any suitable manner, such as by bolts 64, and hasprovided therein a cylinder 65 in which operates a piston 66. Cylinder65 communicates with a port 66' to which one end of pipe 59 isconnected. A gland 61 secured to bracket 63 provents leakage past thepiston 66. The left hand end of piston 66 (Fig. 2) abuts against acrossbar 68 through the opposite ends of which extend a pair of rods 66and 16, the inner ends of said rods being secured to the sliding blockll of pump H, as shown in Figs. 1 and 2. A pair of nuts 12 and 18provided at the outer end of rods 66 and 16 respectively, securecrossbar 68 thereto and permit adjustment of said crossbar to and fromthe piston 66. Secured to rods 69 and 16 intermediate the ends thereofare a pair of blocks I4 and 15 respectively, to which are pivotallyconnected the lower ends of a pair of. levers 16 and 11. These leversare pivoted intermediate their ends on a rod 16 mounted in bracket 66,as shown more particularly in Figs. 2 and 3, and are pivotally attachedat the upper ends thereof as shown at 19, to pintles provided on theouter ends of a crosshead 66. Crosshead 86 is slidably mounted on a rod6| secured to-the upperend of bracket 66 in any suitable manner, such asby a. nut 82. Rod 6| has provided thereon a coil spring 66 which extendsbetween a spring seat 66 mounted adjacent crosshead 66 intermediate theends thereof, and an adjustable spring seat 85. Spring seat is mountednear the right hand end of rod 8i, and may be adjusted by means of nuts66. By this arrangement, it is seen, that when spring 66 is compressedit will urge croahead 66 to the left (Fig. 2) causing levers I6 and TIto swing in a counterclockwise direction, which through their connectionwith rods 68 and 16 place the pump H on stroke in a well known manner.Pump H will remain on stroke until the pressure in the system exceedsthe tension of spring 66. when piston 66 willswing the levers I6 and Hin a clockwise direction, thereby placing the pump on leakage stroke.

Motor," comprises a cylinder 61 having .a piston 48 operating therein.Cylinder 61 is accured to the right hand end (Fig. 2) of pump 11 bymeans of bolts 66, as shown in Figs. 1 and 2. The free end of piston 66engages a crossbar 66 having secured to the opposite ends thereof a pairof rods 6| and 92, the inner ends of which are connected to slidingblock ll of pump H. A gland 63' secured to theleft hand end of cylinder61 prevents leakage of fluid past said piston. Cylinder 81 is providedwith a port 94 to which pipe 6| is connected. From this arrangement itis seen that when pressure is applied to motor 62, sliding block ll willtend to move to the left.

From the above description, the operation of my improved controlmechanism is believed to be obvious. Howevenin order to correlate thevarious elements, a brief rsum of the operation thereof will now begiven.

The operator first adjusts the tension of spring i2 of valve C thedesired amount; for example, if it is desired that fluid discharged fromthe low pressure pump should bypass when the pressure in the systemexceeds I56 pounds per square inch, spring 42 is adjusted to retainvalve 46 upon its seat until this pressure is exceeded. In a likemanner, the tension of spring 83 is adjusted the desired amount, say,for example, to resist a pressure in the system of 1000 pounds persquare inch at the end of the compressing action thereof. Valves A and Bare then adjusted to the position shown in full lines in Fig. l. Theapparatus is now conditioned for operation.

Fluid from pumps H and L will now discharge into the annular chamber 26of cylinder 26 through pipes 5 and 6, valve A, and pipes II and 52.Fluid will' also flow to the lower end of cylinder 22 through pipe 52,check valve 65, valve B, and pipe 53. Pistons 2i and, will now moveupwardly until platen 28 engages the lower end of forming mold 24, andthe upper end of piston 2i engages the abutment at the upper end ofcylinder 26. When this occurs, continued operation of the pumps willcause the pressure to build up in the system and when this pressureexceeds pounds per square inch, piston 46 in valve C will move upwardly,unseating valve 46, thereby permitting fluid from the low pressure pumpL to bypass to makeup tank T through chamber 38, passage 4i,intermediate chamber 31, and pipe 45. The high pressure pump H, however,will continue to operate until the pressure in the system communicatedto motors 66 and 62 is sufllcient to overcome the tension of spring 83.When this occurs sliding block 1| of pump H will be moved to the left(Fig. 2), thereby placing said pump on leakage stroke. Inasmuch as bothmotors 66 and 62 are now operating against the action of spring 62, thepump H is held on leakage stroke at a materially reduced pressure.

The press 3 is now conditioned for operation and the work may be placedin the forming mold 24. When the press has been so loaded the operatorthen adjusts valve members H and I2 of valve A by manipulation of leveri8 to the position shown in Fig. 4. Fluid from the annular chamber 26 ofcylinder 26 will now enter the lower end of chamber i6 of valve Athrough pipe 52, and thence flow through passage l6 and pipe 68 to thestorage or makeup tank T. The pressure in the system is now reduced andspring 83 urges sliding block H to the right (Fig. 2) placing the pumpon stroke. When valve A is adjusted in this manner, it will be notedthat motor 62 is disconnected from the pressure in the system andtherefore is ineflective.

ll ii Fluid under pressure from pump H now enters the upper end ofcylinder 20 through valve A and pipe 50. As a result of the reduction inpressure in the system caused by connecting chamber I to exhaust, asdescribed above spring 42 of valve C will urge valve member 40 upon itsseat, thereby closing the bypass, and fluid from the low pressure pump Lwill also enter the upper end of cylinder 20 through pipes 8 and 5,valve A, and pipe 50. Thus, the combined discharges of pumps H and L areoperative upon piston 2|, which moves downwardly at a comparatively highrate of speed. When platen 21 engages the work the pressure in thesystem again builds up and when this pressure exceeds the tension ofspring 42, which, as previously stated, has been set at 150 pounds persquare inch, piston 46' w ll again unseat valve 0, thereby causing thefluid discharginl from pump L to bypass to makeup tank T. The highpressure pump, however, continues to operate to compress the work in themold until the developed pressure exceeds 1000 pounds per square inch,the pressure to which spring 83 is adjusted. When the pressure in thesystem exceeds this value piston 66 of motor 60 urges sliding block IItoward neutral or leakage stroke position and the pressure may thus bemaintained upon the work for any desired period of time. Inasmuch as thecross sectional area of piston 23 is greater than that of piston 2|, anddue to the connection of cylinder 22 with pipe 50 through p pe 56, valve13. and pipe 53, the piston 23 will be held in its uppermost positionagainst the pressure exerted upon the work by piston 2|. ter thematerials in the mold have been under compression the desired period oftime, the operator actuates valve members 30 and 3| of valve B bymanipulation of lever 32 to the position shown in Fig. 5. When valve Bis so adjusted the fluid in cylinder 22 will bypass to storage tank Tthrough pipe 53, chamber 29 of valve B, and pipe 54. As a result thepressure in the system is again reduced and spring 83 again places pumpH on stroke, ca sing flu d under pressure to be discharged throu h pipeand thence to the upper; end of cylinder 20, causing piston 2! tocontinue its downward movement. When the pressu e decreases to 150pounds per square inch low pressure pump L will also become effective toassist in this down ward movement of platen 27. Platen 21 continues tomove downwardly in this'manner. causing the work formed in the mold tobe ejected therefrom, which then may be removed by the operator.

This downwa d movement of piston 2! may continue until it engages thelower end of cylinder 20. when the pressure in the system again buildsup. When this pressure exceeds 1000 pounds per square inch, pump H willaga n be placed on neutral or leakage stroke by the fluid motor 60 ashereinbefore described. However, when the work is ejected from the mold,the operator usually moves levers l3 and 32 of valves Aand Brespectively to the full line position shown'in Fig. 1 to condition thepress for another operation. Pistons 2i and 23 will then be moved totheir uppermost positions as previously described, by the combineddischarges of pumps H and L. When piston 2| reaches the upper end ofcylinder 20, the pressure in the system again builds up. At this time itwill be remembered that both of the fluid motors Eli and 62 operate inunison, to adjust the pump to, and maintain the same on leakage strokeposition. The pressure required to maintain the pump on leakage stroke,therefore, is materially reduced.

It therefore is seen that a highly efiicient control mechanism has'beenprovided. By reducing the pressure required to maintain the pump onleakage stroke, the load imposed on the motor M is also reduced, withthe result that undue strains on the apparatus are not only minimized,but the cost of operation thereof is greatly reduced. It also isbelieved to be clear that pump H and the control mechanism associatedtherewith form a unitary construction which is adaptable for generaluse.

The invention therefore, it is to be understood, is not to be limited tothe embodiment herein shown, since it may be embodied in other forms,all coming within the scope of the claims which follow.

What is claimed is:

1. In a fluid system, the combination with a variable stroke pump, of afluid motor operated by said pump, means for controlling the operationof said motor including a valve, means for placing said, pump on stroke,means for returning said pump to leakage stroke position, said lastmentioned means comprising a pair of servo motors, one of said servomotors being constantly connected to the discharge pressure in thesystem and adapted to return the pump to leakage stroke position whenthe pressure in the system exceeds a predetermined value, means foractuating said valve to control the operation of said fluid motor and toconnect the second of said servo motors to said discharge pressurewhereby said second fluid motor operates in the same direction as saidfirst mentioned servo motor to return the pump to and maintain the sameon leakage stroke position at a comparatively low pressure.-

2. In a fluid control system, the combination with a variable strokepump, of resilient means for placing said pump on stroke, means foractuating said pump to and retaining the same on leakage strokeposition, said last mentioned means comprising a pair of fluid motors,one of said motors being constantly connected to the discharge pressurein the system, and a valve for connecting the other of said motors tosaid discharge pressure, whereby the combined ac tion of said motorsmaintains said pump on leakage stroke position at a relatively lowpressure.

3. In a fluid control system, the combination with a variable strokepump, of adjustable resilient means for placing said pump on stroke,means for actuating said pump to and retaining the same on leakagestroke position, said last mentioned means comprising a pair of fluidmotors, one of said motors being constantly connected to the dischargepressure in the system and adaptable to return said pump to leakagestroke position when the pressure in the system exceeds the tension ofsaid resilient means, a valve for connecting the other of said motors tosaid discharge pressure, whereby the combined action of said motorsmaintains the pump on leakage stroke position at a relatively lowpressure.

4. In a fluid system, the combination with a variable stroke pump, of a.fluid motor operated by said pump, adjustable resilient means forplacing said pump on stroke, means for controlling the operation of saidfluid motor including a valve, means for returning said pump to leakagestroke position, said last mentioned means comprising a pair of servomotors, one of said servo motors being constantly connected to thedischarge pressure in the system and adapted to return the 5. In a fluidcontrol system, the combination' with a high pressure pump and a lowpressure pump, resilient means for placing said high pressure pump onstroke, automatic bypass means for rendering said low pressure pumpineflective when the pressure in the system exceeds a predeterminedvalue, and a plurality of means for returning said high pressure pump toleakage stroke position, one of said means being adapted to maintainsaid high pressure pump on leakage stroke position at a comparativelyhigh pressure, and means for conditioning another of said last mentionedmeans for operation, whereby said high pressure pump is maintained onleakage stroke position at a comparatively low pressure by the combinedaction of said pump actuating means.

6. In a fluid control system, the combination with a high pressure pumpand a low pressure pump, adjustable resilient means for placing saidhigh pressure pump on stroke, automatic bypass means for rendering saidlow pressure pump ineflective when the pressure in the system exceeds apredetermined value, and a plurality of fluid motors for returning saidhigh pressure pump to leakage stroke position, one of said motors beingadapted to maintain said high pressure pump in neutral position at acomparatively high pressure, and valve means for conditioning another ofsaid fluid motors for operation where by said high pressure pump ismaintained on leakage stroke position at a comparatively low pressure bythe combined action of said fluid motors.

'7. In a fluid system, the combination with a fluid motor comprising apair of cylinders, a pressing piston operative in one of said cylindersand a holding piston operative in the other of said cylinders, saidpistons being adapted for relative movement, of a pump for actuatingsaid pistons, means for placing said pump on discharge stroke, hydraulicconnections between said pump and said cylinders, a pair of valves forcontrolling the sequence of operation of said pistons, said valve whenadjusted to one position causing both of said pistons to movesimultaneously in one direction, means for actuating said pump towardleakage stroke position and retaining the same in said position whensaid pistons reach the limit of their travel in said direction, meansfor adjusting one of said valves to another of its positions ofadjustment causing said pressing piston to move toward said holdingpiston while retaining the latter against movement, and means foractuating the other of said valves to another of its positions ofadjustment, whereby said holding piston will move in the same directionas said pressing piston moves in its last mentioned movement.

8. In a fluid system, the combination with a fluid motor comprising apair of cylinders, a pressing piston operative in one of said cylinders,and a holding piston operative in the other of said cylinders, saidpistons being adapted for relative movement, of a pump for actuatingsaid pistons, means for placing said pump on discharge stroke, valvemeans for controlling the sequence of operation of said pistons, saidvalves when adjusted to one position causing said pressing piston tomove toward said holding piston while retaining the latter in holdingposition, means for actuating said pump toward leakage stroke positionand retaining the same in said position at a relatively high pressure,means for actuatingsaid valve means to another position of adjustmentcausing said pressing piston to move away from said holding piston, andadditional means operative in conjunction with said pump actuating meansfor actuating said pump toward leakage stroke position when saidpressing piston reaches the limit of its travel away from said holdingpiston, whereby said pump is held on leakage stroke at a reducedpressure.

9. In a fluid system, the combination with a fluid motor, comprising apair of cylinders, a pressing piston operative in one of said cylindersand a holding piston operative in the other of said cylinders, saidpistons being adapted for relative movement, of means for operating saidpistons including a high pressure pump and a low pressure pump,automatic means for rendering said low pressure pump ineifective whenthe pressure delivered to said pistons exceeds a predetermined value,adjustable resilient means for maintaining said high pressure pump onstroke,

a plurality of servo motors for returning said high pressure pump toleakage stroke position under predetermined conditions, one of saidservo motors being constantly connected to the discharge pressure insaid system, a plurality of valves for controlling the sequence ofoperation of said pistons, said valves when operated to one positioncausing said pistons to move simultaneously in one direction by thecombined dis-- charges of said pumps, and at the same time connectingthe other oi! said servo motors to said discharge pressure, whereby,when said pistons reach the limit of their travel in said direction thepressure developed in said system first actuates said automatic means torender said low pressure pump ineffective, and at a higher predeterminedpressure said high pressure pump is rendered ineffective by the combinedaction of said servo motors, means for actuating one of said valves toanother of its positions of adjustment, thereby causing said pressingpiston to move toward said holding piston, while retaining the latteragainst movement, and at the same time disconnecting one of said servomotors whereby said pump is actuated toward leakage stroke position at astill higher predetermined pressure, and means for actuating another ofsaid valves to another position of adjustment, whereby said holdingpiston moves in the same direction as said pressing piston.

HENRY W. LANDENBERGER.

